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Add 'active_in' column to pg_replication_slots.

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Right now it is visible whether a replication slot is active in any
session, but not in which.  Adding the active_in column, containing the
pid of the backend having acquired the slot, makes it much easier to
associate pg_replication_slots entries with the corresponding
pg_stat_replication/pg_stat_activity row.

This should have been done from the start, but I (Andres) dropped the
ball there somehow.

Author: Craig Ringer, revised by me Discussion:
CAMsr+YFKgZca5_7_ouaMWxA5PneJC9LNViPzpDHusaPhU9pA7g@mail.gmail.com
This commit is contained in:
Andres Freund
2015-04-21 11:51:06 +02:00
parent 528c2e44ab
commit d811c037ce
9 changed files with 47 additions and 28 deletions
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30
src/backend/replication/slot.c
View File

@@ -262,7 +262,7 @@ ReplicationSlotCreate(const char *name, bool db_specific,
* be doing that. So it's safe to initialize the slot.
*/
Assert(!slot->in_use);
Assert(!slot->active);
Assert(slot->active_pid == 0);
slot->data.persistency = persistency;
slot->data.xmin = InvalidTransactionId;
slot->effective_xmin = InvalidTransactionId;
@@ -291,8 +291,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
volatile ReplicationSlot *vslot = slot;
SpinLockAcquire(&slot->mutex);
Assert(!vslot->active);
vslot->active = true;
Assert(vslot->active_pid == 0);
vslot->active_pid = MyProcPid;
SpinLockRelease(&slot->mutex);
MyReplicationSlot = slot;
}
@@ -314,7 +314,7 @@ ReplicationSlotAcquire(const char *name)
{
ReplicationSlot *slot = NULL;
int i;
bool active = false;
int active_pid = 0;
Assert(MyReplicationSlot == NULL);
@@ -331,8 +331,9 @@ ReplicationSlotAcquire(const char *name)
volatile ReplicationSlot *vslot = s;
SpinLockAcquire(&s->mutex);
active = vslot->active;
vslot->active = true;
active_pid = vslot->active_pid;
if (active_pid == 0)
vslot->active_pid = MyProcPid;
SpinLockRelease(&s->mutex);
slot = s;
break;
@@ -345,10 +346,11 @@ ReplicationSlotAcquire(const char *name)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("replication slot \"%s\" does not exist", name)));
if (active)
if (active_pid != 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_IN_USE),
errmsg("replication slot \"%s\" is already active", name)));
errmsg("replication slot \"%s\" is already active for pid %d",
name, active_pid)));
/* We made this slot active, so it's ours now. */
MyReplicationSlot = slot;
@@ -363,7 +365,7 @@ ReplicationSlotRelease(void)
{
ReplicationSlot *slot = MyReplicationSlot;
Assert(slot != NULL && slot->active);
Assert(slot != NULL && slot->active_pid != 0);
if (slot->data.persistency == RS_EPHEMERAL)
{
@@ -380,7 +382,7 @@ ReplicationSlotRelease(void)
volatile ReplicationSlot *vslot = slot;
SpinLockAcquire(&slot->mutex);
vslot->active = false;
vslot->active_pid = 0;
SpinLockRelease(&slot->mutex);
}
@@ -460,7 +462,7 @@ ReplicationSlotDropAcquired(void)
bool fail_softly = slot->data.persistency == RS_EPHEMERAL;
SpinLockAcquire(&slot->mutex);
vslot->active = false;
vslot->active_pid = 0;
SpinLockRelease(&slot->mutex);
ereport(fail_softly ? WARNING : ERROR,
@@ -477,7 +479,7 @@ ReplicationSlotDropAcquired(void)
* scanning the array.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_EXCLUSIVE);
slot->active = false;
slot->active_pid = 0;
slot->in_use = false;
LWLockRelease(ReplicationSlotControlLock);
@@ -749,7 +751,7 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
/* count slots with spinlock held */
SpinLockAcquire(&s->mutex);
(*nslots)++;
if (s->active)
if (s->active_pid != 0)
(*nactive)++;
SpinLockRelease(&s->mutex);
}
@@ -1227,7 +1229,7 @@ RestoreSlotFromDisk(const char *name)
slot->candidate_restart_valid = InvalidXLogRecPtr;
slot->in_use = true;
slot->active = false;
slot->active_pid = 0;
restored = true;
break;

13
src/backend/replication/slotfuncs.c
View File

@@ -158,7 +158,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
Datum
pg_get_replication_slots(PG_FUNCTION_ARGS)
{
#define PG_GET_REPLICATION_SLOTS_COLS 8
#define PG_GET_REPLICATION_SLOTS_COLS 9
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
@@ -206,7 +206,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
TransactionId xmin;
TransactionId catalog_xmin;
XLogRecPtr restart_lsn;
bool active;
pid_t active_pid;
Oid database;
NameData slot_name;
NameData plugin;
@@ -227,7 +227,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
namecpy(&slot_name, &slot->data.name);
namecpy(&plugin, &slot->data.plugin);
active = slot->active;
active_pid = slot->active_pid;
}
SpinLockRelease(&slot->mutex);
@@ -251,7 +251,12 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
else
values[i++] = database;
values[i++] = BoolGetDatum(active);
values[i++] = BoolGetDatum(active_pid != 0);
if (active_pid != 0)
values[i++] = Int32GetDatum(active_pid);
else
nulls[i++] = true;
if (xmin != InvalidTransactionId)
values[i++] = TransactionIdGetDatum(xmin);